System and method for increasing solar cell efficiency

ABSTRACT

A solar cell management system for increasing the efficiency and power output of a solar cell and methods for making and using the same. The management system provides an electric field across an individual solar cell, an array of solar cells configured as a panel, or a group of solar panels. The imposed electric field exerts a force on both the electrons and holes created by light incident on the solar cell and accelerates the electron-hole pairs towards the electrodes of the solar cell. Compared to conventional solar cells, these accelerated electron-hole pairs travel a shorter distance from creation (by incident optical radiation) and spend less time within the solar cell material, therefore the electron-hole pairs have a lower likelihood of recombining within the cells&#39; semiconductor&#39;s material. This reduction in the electron-hole recombination rate results in an overall increase in the solar cells&#39; efficiency and greater power output.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of co-pending U.S. patentapplication Ser. No. 16/155,648, filed Oct. 9, 2018, which is acontinuation of U.S. patent application Ser. No. 16/042,758, filed Jul.23, 2018, now U.S. Pat. No. 10,355,489, which is a continuation of U.S.patent application Ser. No. 14/628,079, filed Feb. 20, 2015, now U.S.Pat. No. 10,069,306, which claims the benefit of U.S. ProvisionalApplication Ser. No. 61/943,127, filed Feb. 21, 2014; U.S. ProvisionalApplication Ser. No. 61/943,134, filed Feb. 21, 2014; U.S. ProvisionalApplication Ser. No. 61/947,326, filed Mar. 3, 2014; and U.S.Provisional Application Ser. No. 62/022,087, filed Jul. 8, 2014, thedisclosures of which are hereby incorporated by reference in theirentirety and for all purposes.

FIELD

The present disclosure relates generally to photovoltaic devices andmore specifically, but not exclusively, to systems and methods formaximizing the power or energy generated and the overall efficiency ofone or more solar cells, for example, by applying and adjusting anexternal electric field across the solar cells.

BACKGROUND

A solar cell (also called a photovoltaic cell) is an electrical devicethat converts the energy of light directly into electricity by a processknown as “the photovoltaic effect.” When exposed to light, the solarcell can generate and support an electric current without being attachedto any external voltage source.

The most common solar cell consists of a p-n junction 110 fabricatedfrom semiconductor materials (e.g., silicon), such as in a solar cell100 shown in FIG. 1. For example, the p-n junction 110 includes a thinwafer consisting of an ultra-thin layer of n-type silicon on top of athicker layer of p-type silicon. Where these two layers are in contact,an electrical field (not shown) is created near the top surface of thesolar cell 100, and a diffusion of electrons occurs from the region ofhigh electron concentration (the n-type side of the p-n junction 110)into the region of low electron concentration (the p-type side of thep-n junction 110).

The p-n junction 110 is encapsulated between two conductive electrodes101 a, 101 b. The top electrode 101 a is either transparent to incident(solar) radiation or does not entirely cover the top of the solar cell100. The electrodes 101 a, 101 b can serve as ohmic metal-semiconductorcontacts that are connected to an external load 30 that is coupled inseries. Although shown as resistive only, the load 30 can also includeboth resistive and reactive components.

Typically, multiple solar cells 100 can be coupled (in series and/orparallel) together to form a solar panel 10 (shown in FIG. 2). Withreference to FIG. 2, a typical installation configuration using at leastone solar panel 10 is shown. The solar panels 10 can be connected eitherin parallel as shown in FIG. 2, series, or a combination thereof, andattached to a load, such as an inverter 31. The inverter 31 can includeboth resistive and reactive components.

Returning to FIG. 1, when a photon hits the solar cell 100, the photoneither: passes straight through the solar cell material—which generallyhappens for lower energy photons; reflects off the surface of the solarcell; or preferably is absorbed by the solar cell material—if the photonenergy is higher than the silicon band gap—generating an electron-holepair.

If the photon is absorbed, its energy is given to an electron in thesolar cell material. Usually this electron is in the valence band and istightly bound in covalent bonds between neighboring atoms, and henceunable to move far. The energy given to the electron by the photon“excites” the electron into the conduction band, where it is free tomove around within the solar cell 100. The covalent bond that theelectron was previously a part of now has one fewer electron—this isknown as a hole. The presence of a missing covalent bond allows thebonded electrons of neighboring atoms to move into the hole, leavinganother hole behind. In this way, a hole also can move effectivelythrough the solar cell 100. Thus, photons absorbed in the solar cell 100create mobile electron-hole pairs.

The mobile electron-hole pair diffuses or drifts toward the electrodes101 a, 101 b. Typically, the electron diffuses/drifts towards thenegative electrode, and the hole diffuses/drifts towards the positiveelectrode. Diffusion of carriers (e.g., electrons) is due to randomthermal motion until the carrier is captured by electrical fields.Drifting of carriers is driven by electric fields established across anactive field of the solar cell 100. In thin film solar cells, thedominant mode of charge carrier separation is drifting, driven by theelectrostatic field of the p-n junction 110 extending throughout thethickness of the thin film solar cell. However, for thicker solar cellshaving virtually no electric field in the active region, the dominantmode of charge carrier separation is diffusion. The diffusion length ofminor carriers (i.e., the length that photo-generated carriers cantravel before they recombine) must be large in thicker solar cells.

Ultimately, electrons that are created on the n-type side of the p-njunction 110, “collected” by the p-n junction 110, and swept onto then-type side can provide power to the external load 30 (via the electrode101 a) and return to the p-type side (via the electrode 101 b) of thesolar cell 100. Once returning to the p-type side, the electron canrecombine with a hole that was either created as an electron-hole pairon the p-type side or swept across the p-n junction 110 from the n-typeside.

As shown in FIG. 1, the electron-hole pair travels a circuitous routefrom the point the electron-hole pair is created to the point where theelectron-hole pair is collected at the electrodes 101 a, 101 b. Sincethe path traveled by the electron-hole pair is long, ample opportunityexists for the electron or hole to recombine with another hole orelectron, which recombination results in a loss of current to anyexternal load 30. Stated in another way, when an electron-hole pair iscreated, one of the carriers may reach the p-n junction 110 (a collectedcarrier) and contribute to the current produced by the solar cell 100.Alternatively, the carrier can recombine with no net contribution tocell current. Charge recombination causes a drop in quantum efficiency(i.e., the percentage of photons that are converted to electric currentwhen the solar cell 100), and, therefore, the overall efficiency of thesolar cell 100.

The cost of the solar cell 100 or the solar panel 10 is typically givenin units of dollars per watts of peak electrical power that can begenerated under normalized conditions. High-efficiency solar cellsdecrease the cost of solar energy. Many of the costs of a solar powersystem or plant are proportional to the number of solar panels requiredas well as the (land) area required to mount the panels. A higherefficiency solar cell will allow for a reduction in the number of solarpanels required for a given energy output and the required area todeploy the system. This reduction in the number of panels and space usedmight reduce the total plant cost, even if the cells themselves are morecostly.

The ultimate goal is to make the cost of solar power generationcomparable to, or less than, conventional electrical power plants thatutilize natural gas, coal, and/or fuel oil to generate electricity.Unlike most conventional circuit of generating electric power thatrequire large, centralized power plants, solar power systems can bedeployed at large centralized locations by electric utilities, oncommercial buildings to help offset the cost of electric power, and evenon a residence-by-residence basis.

Recent attempts to reduce the cost and increase the efficiency of solarcells include testing various materials and different fabricationtechniques used for the solar cells. Another approach attempts toenhance the depletion region formed around the p-n junction 110 forenhancing the movement of charge carriers through the solar cell 100.For example, see U.S. Pat. No. 5,215,599, to Hingorani, et al.(“Hingorani”), filed on May 3, 1991, and U.S. Pat. No. 8,466,582, toFornage (“Fornage”), filed on Dec. 2, 2011, claiming priority to a Dec.3, 2010 filing date, the disclosures of which are hereby incorporated byreference in their entireties and for all purposes.

However, these conventional approaches for enhancing the movement ofcharge carriers through the solar cell 100 require a modification of thefundamental structure of the solar cell 100. Hingorani and Fornage, forexample, disclose applying an external electric field to the solar cellusing a modified solar cell structure. The application of the externalelectric field requires a voltage to be applied between electrodesinducing the electric field (described in further detail with referenceto equation 2, below). Without modifying the fundamental structure ofthe solar cell 100, applying the voltage to the existing electrodes 101a, 101 b of the solar cell 100 shorts the applied voltage through theexternal load 30. Stated in another way, applying voltage to theelectrodes 101 a, 101 b of the solar 100 is ineffective for creating anexternal electric field and enhancing the movement of charge carriers.Accordingly, conventional approaches—such as disclosed in Hingorani andFornage—necessarily modify the fundamental structure of the solar cell100, such as by inserting an external (and electrically isolated) set ofelectrodes on the base of the solar cell 100. There are severaldisadvantages with this approach.

For example, the external electrodes must be placed on the solar cell100 during the fabrication process—it is virtually impossible toretrofit the external electrodes to an existing solar cell or panel.This modification to the fabrication process significantly increases thecost of manufacturing and decreases the manufacturing yield.Additionally, placement of the external electrodes over the front, orincident side, of the solar cell 100 reduces the optical energy whichreaches the solar cell 100, thereby yielding a lower power output.

As a further disadvantage, to yield significant improvements in poweroutput of the solar cell 100, sizeable voltages must be applied to theexternal electrodes of the solar cell 100. For example, Fornagediscloses that voltages on the order of “1,000's” of volts must beplaced on the external electrodes for the applied electric field to beeffective and increase the power output of the solar cell 100. Themagnitude of this voltage requires special training for servicing aswell as additional high voltage equipment and wiring that does notpresently exist in existing or new solar panel deployments. As anexample, an insulation layer between the external electrodes and thesolar cell 100 must be sufficient to withstand the high applied voltage.In the event of a failure of the insulation layer, there is asignificant risk of damage to not only the solar cell 100, but also allsolar panels 10 connected in series or parallel to the failed solar cellas well as the external load 30 (or the inverter 31).

As a further disadvantage, varying illumination conditions (e.g., due tocloud coverage of the sun and/or normal weather fluctuations) can causeinstability in the power output of conventional solar cells and solarpanels. For example, with reference to FIG. 2, the inverter 31 typicallyrequires a static, non-varying voltage and current input. As shown inFIG. 2, the solar panels 10 provide the input voltage and current to theinverter 31. However, time-varying illumination conditions can cause theoutput from solar panels 10 to fluctuate (e.g., on the order of secondsor less). The fluctuation of the voltage and current supplied to theinverter 31 compromises the quality of the power output by the inverter31, for example, in terms of frequency, voltage, and harmonic content.Conventional efforts to combat varying illumination conditions includeplacing batteries or capacitors at the input of the inverter 31 and,unfortunately, only minimize these variations.

In view of the foregoing, a need exists for an improved solar cellsystem and method for increased efficiency and power output, such aswith increased mobility of electron-hole pairs, in an effort to overcomethe aforementioned obstacles and deficiencies of conventional solar cellsystems.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exemplary top-level cross-sectional diagram illustrating anembodiment of a solar cell of the prior art.

FIG. 2 is an exemplary top-level block diagram illustrating oneembodiment of a solar panel array of the prior art using the solar cellsof FIG. 1.

FIG. 3 is an exemplary top-level block diagram illustrating anembodiment of a solar cell management system.

FIG. 4 is an exemplary block diagram illustrating an alternativeembodiment of the solar cell management system of FIG. 3, wherein asolar panel array is coupled to a voltage source through a switch.

FIGS. 5A-D are exemplary waveforms illustrating the applied voltage as afunction of time of the inputs and outputs of the switch used with thesolar panel array of FIG. 4.

FIG. 6 is an exemplary block diagram illustrating another alternativeembodiment of the solar cell management system of FIG. 3, wherein asolar panel array is coupled to a voltage pulser circuit.

FIG. 7 is an exemplary waveform illustrating the applied voltage as afunction of time used with the solar panel array of FIG. 6.

FIG. 8 is an exemplary block diagram illustrating one embodiment of thevoltage pulser circuit of FIG. 6.

FIG. 9A is an exemplary block diagram illustrating an alternativeembodiment of the solar cell management system of FIG. 4, wherein thesolar cell management system includes a control circuit.

FIG. 9B is an exemplary flow-chart illustrating a state diagram for thecontrol circuit shown in FIG. 9A.

FIG. 10A is an exemplary block diagram illustrating an alternativeembodiment of the solar cell management system of FIG. 6, wherein thesolar cell management system includes a control circuit.

FIG. 10B is an exemplary flow-chart illustrating a state diagram for thecontrol circuit shown in FIG. 10A.

FIGS. 11A-C are exemplary waveforms illustrating an embodiment of therelationship between applied voltage, pulse frequency, and pulse widthto the improved current output of the photovoltaic device of FIG. 3.

It should be noted that the figures are not drawn to scale and thatelements of similar structures or functions are generally represented bylike reference numerals for illustrative purposes throughout thefigures. It also should be noted that the figures are only intended tofacilitate the description of the preferred embodiments. The figures donot illustrate every aspect of the described embodiments and do notlimit the scope of the present disclosure.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Since currently-available solar cell systems fail to maximize the poweroutput of a photovoltaic cell, a solar cell system that increases themobility of electron-hole pairs and reduces the recombination current ina semiconductor material can prove desirable and provide a basis for awide range of solar cell systems, such as to increase the efficiency andpower output of solar cells configured as a solar panel. This result canbe achieved, according to one embodiment disclosed herein, by a solarcell management system 300 as illustrated in FIG. 3.

Turning to FIG. 3, the solar cell management system 300 is suitable foruse with a wide range of photovoltaic devices. In one embodiment, thesolar cell management system 300 can be suitable for use with the solarcell 100 shown in FIG. 1. For example, the solar cell 100 can representany suitable generation of solar cells such as wafer-based cells ofcrystalline silicon (first generation), thin film solar cells includingamorphous silicon cells (second generation), and/or third generationcells. The solar cell management system 300 advantageously can be usedwith any generation of solar cell 100 without structuralmodification—and the associated drawbacks.

In another embodiment, the solar cell management system 300 can besuitable for use with multiple solar cells 100, such as the solar panels10 shown in FIG. 2. As previously discussed, multiple solar cells 100can be coupled (in series and/or parallel) together to form a solarpanel 10. The solar panels 10 can be mounted on a supporting structure(not shown) via ground mounting, roof mounting, solar tracking systems,fixed racks, and so on and can be utilized for both terrestrial andspace borne applications. Similarly, the solar cell management system300 advantageously can be used with any generation of solar panel 10without structural modification—and the associated drawbacks—of thesolar panel 10.

As shown in FIG. 3, the photovoltaic device 200 cooperates with anelectric field 250. In some embodiments, the polarity of the electricfield 250 can be applied in either the same direction or the reversedirection as the polarity of the electrodes 101 a, 101 b (shown inFIG. 1) in the photovoltaic device 200. For example, if applying theelectric field 250 in the same direction as the polarity of theelectrodes 101 a, 101 b in the photovoltaic device 200, the electricfield 250 acts on the electron-hole pairs in the photovoltaic device 200to impose a force—e⁻E or h⁺E on the electron or hole,respectively—thereby accelerating the mobility of the electron and holetowards respective electrodes. Alternatively, if the polarity of theelectric field 250 is reversed, the mobility of the electron-hole pairsin the photovoltaic device 200 decreases, thereby increasing therecombination current within the photovoltaic device 200. Accordingly,the efficiency of the photovoltaic device 200 can be diminished asdesired, such as for managing the power output of the photovoltaicdevice 200.

Furthermore, the electric field 250 applied to the photovoltaic device200 can be static or time varying as desired. In the case where theelectric field 250 is time varying, the electric field 250 has a timeaveraged magnitude that is non-zero. Stated in another way, the netforce on the electrons and holes is non-zero to provide increasedmobility in the electron-hole pairs of the photovoltaic device 200.

If applied to the conventional solar cell 100 of FIG. 1, in the absenceof an external load 30 (shown in FIG. 1), an external voltage can beapplied across the electrodes 101 a, 101 b of the solar cell 100 tocreate the electric field 250. In one embodiment, the electric field 250(e.g., between the electrodes 101 a, 101 b) is defined by Equation 1:

$\begin{matrix}{E = \frac{( {V_{App} - V_{P}} )}{t}} & ( {{Equation}\mspace{20mu} 1} )\end{matrix}$

In Equation 1, E represents the electric field 250, V_(App) is thevoltage applied externally to the photovoltaic device 200, V_(P) is thevoltage output of the photovoltaic device 200 (e.g., 30 volts), and t isthe thickness of the semiconductor material in the photovoltaic device200 from electrode 101 a to 101 b. For example, assumingV_(APP)−V_(P)=200 Volts (nominally) and a thickness t of about 0.02 cm,the electric field 250 is about 10K Volts/cm. It can be seen fromEquation 1 that as the thickness t of the photovoltaic device 200decreases (e.g., less than 0.01 cm), higher electric fields 250 can begenerated using the same or lower voltages.

As discussed above, the photovoltaic device 200 typically drives anexternal load, such as the load 30 of the solar cell 100. With referenceto Equation 1, if applying an external voltage V_(App) directly to thephotovoltaic device 200 that drives the external load 30, the externalload 30 can include resistive components that draw current from thesource of the applied voltage V_(App). Stated in another way, applyingthe external voltage V_(App) to the photovoltaic device 200 caneffectively deliver power to the overall circuit represented by Equation2:

$\begin{matrix}{{Power}_{Input} = \frac{( V_{App} )^{2}}{R_{L}}} & ( {{Equation}\mspace{20mu} 2} )\end{matrix}$

In Equation 2, R_(L) represents the impedance of the external load 30.In some cases, the input power can be substantially greater than thepower output of the photovoltaic device 200. Accordingly, the solar cellmanagement system 300 is configured to apply the electric field 250across the photovoltaic device 200 without injecting more energy thanthe photovoltaic device 200 is capable of producing or more energy thanwould be gained by applying the electric field across the photovoltaicdevice 200.

The solar cell management system 300 can apply the external voltageV_(App) to the photovoltaic device 200 using any suitable circuitdescribed herein, including using a switch 55 as shown in FIG. 4.Turning to FIG. 4, the photovoltaic device 200 can represent any numberof photovoltaic devices such as the solar cell 100 and/or the solarpanels 10 as illustrated. The solar panels 10 are connected to theswitch 55, such as a single pole, double throw (or three-way) switch asshown. In one embodiment, the switch 55 is also coupled to a voltagesource 50 and an external load R_(L) (e.g., shown as the inverter 31).The inverter 31 can convert a DC voltage and current into an AC voltageand current, which is typically compatible in voltage and frequency withconventional AC power grids. The output frequency of the inverter 31 andthe amplitude of the AC current/voltage can be based upon country,location, and local grid requirements.

The voltage source 50 can include any suitable circuit for maintaining aconstant voltage, including ideal voltage sources, controlled voltagesources, and so on. However, in some embodiments—such as the embodimentshown below with reference to FIG. 9A—the voltage source 50 can have avariable, adjustable output (e.g., time varying voltage). A switchcontrol (or controller) 45 is coupled to the switch 55 to control theduration of connection and/or the frequency of switching, such asbetween the voltage source 50 and the inverter 31 to the solar panels10. The switch controller 45 can be preset to operate at a fixedswitching duration D and switching frequency f (shown in FIGS. 5A-C).The voltage applied in the first position of the switch 55 can be fixedand based on the voltage source 50. In some embodiments, the magnitudeof the voltage applied by voltage source 50, the duration D ofconnection, and/or the frequency f of switching can be preset and/orvary based on load conditions.

For example, the switch 55 connects the solar panels 10 with the voltagesource 50 in a first position (as shown with the arrow in the switch 55of FIG. 4). When connected in the first position, the voltage source 50applies a voltage V_(APP) across the electrodes 101 a, 101 b (shown inFIG. 1) of the solar panels 10 and induces the electric field 250 (shownin FIG. 3) across each solar panel 10. Once the electric field 250 hasbeen established across the solar panels 10, the switch 55 switches toconnect the solar panels 10 to the inverter 31 (i.e., the load R_(L)) ina second position. Accordingly, the voltage source 50 can provide theelectric field 250 without being connected to the solar panels 10 andthe inverter 31 at the same time. Therefore, with reference again toEquation 2, applying the external voltage V_(APP) does not allow theload R_(L) (e.g., the inverter 31) to draw current directly from thevoltage source 50.

Application of the electric field 250 to the solar panels 10 canincrease the current and power output of the solar panels 10 by apredetermined amount when the solar panels 10 subsequently are connectedto the inverter 31 in the second position. The predetermined amount isdependent upon an intensity of light incident on the solar panels 10,the voltage applied V_(APP) to the solar panels 10 by the voltage source50, the thickness of the solar panels 10, the frequency f that thevoltage source 50 is connected to the solar panels 10, and the dutycycle of the switching process between the first position and the secondposition—with the duty cycle being defined as the amount of time thatthe solar panels 10 are connected to the voltage source 50 divided by1/f the switching time (i.e., multiplied by the frequency f or dividedby the total period of the signal). It should be noted that the switchduration time D, the switching frequency f, and the duty cycle are allinterrelated quantities such that quantifying any two of the quantitiesallows for determination of the third quantity. For example, specifyingthe switching frequency and the duty cycle allows for determination ofthe switch duration time D. For example, under high intensity lightconditions, the improvement in power output can be on the order of 20%;under low light conditions, 50+%.

The embodiment shown in FIG. 4 advantageously provides the electricfield 250 to the photovoltaic device 200 without the need to modify thesolar panels 10 and/or solar cells 100 to include additional, externalelectrodes.

In some embodiments, an energy storage device—such as a capacitor 41, aninductor 42, and/or a battery 43—can be placed before the inverter 31 tomitigate any voltage drop-out being seen by the inverter 31 while theswitch 55 is in the first position. Accordingly, while the inverter 31(i.e., load) is disconnected from the solar panels 10 when the switch 55is in the first position and the electric field 250 is being establishedacross the solar panels 10 (i.e., switching time D shown in FIGS. 5A-D),the energy storage device supplies energy to the inverter 31 to keepcurrent flowing during this switched period. Stated in another way, theenergy storage device can discharge while the solar panels 10 aredisconnected from the inverter 31.

Therefore, a constant voltage from the voltage source 50—which in turncreates the electric field 250—need not be applied continuously to seean improvement in the power output of the solar panels 10. For example,with duration switching times D of nominally 10-2000 ns, V_(App)'s ofnominally 100-500+ Volts, and a switching frequency f of 20 μseconds,the duty cycle of nominally 0.1-10% can be used. The inductor 42, thecapacitor 41, and/or the battery 43 are chosen to be of sufficient sizeto provide enough discharge while the solar panels 10 are disconnectedwhile the electric field 250 is being placed across the solar panels 10so as not to cause a drop out on the output of the inverter 31.

For example, the size of the capacitor 41 that is placed across the load(e.g., the inverter 31) is determined by the acceptable voltage droopthat the inverter 31 can tolerate during the switching time D. Forexample, if the voltage droop during the switching time D is not to beless than 90% maximum voltage generated by the photovoltaic device 200,the capacitor needs to be sized such according to Equation 3:

$\begin{matrix}{C_{41} = \frac{- D}{R_{L}{\ln({MaxV})}}} & ( {{Equation}\mspace{20mu} 3} )\end{matrix}$

In Equation 3, D is the duration the switch is connected to the voltagesource 50 and MaxV is the percentage of the maximum voltage required(e.g., 90% in the example above). In a similar manner, the inductanceand/or the battery can be calculated.

FIG. 5A illustrates control voltage as a function of time from theswitch controller 45 to activate and control the switch 55 using thesolar cell management system 300 of FIG. 4. In this example, the solarpanels 10 are disconnected from the inverter 31 and connected to thevoltage source 50 in the first position of the switch 55 for theduration D, which is repeated every 1/f seconds. FIG. 5B illustrates thevoltage as a function of time from the voltage source 50 provided to theswitch 55 at the first position. FIG. 5C illustrates the output voltageof the switch 55 from the solar panels 10 (when wired in parallel) as afunction of time at the output of the switch 55 that couples to theinverter 31 in the second position. Similarly, FIG. 5D illustrates thevoltage as a function of time at the output of the switch 55 thatcouples to the inverter 31 having a capacitor 41 coupled there between.

The drop in voltage seen by the inverter 31 shown in FIG. 5D at the endof the switching duration D is designated the voltage droop discussedabove. The voltage droop is dependent on the size of the capacitor 41,the inductor 42, and/or the battery 43. In one example of the system 300that does not include the capacitor 41, the inductor 42, or the battery43, the voltage applied across the input of the inverter 31 appears asthe output voltage illustrated in FIG. 5C.

FIG. 6 illustrates an alternative embodiment of the solar cellmanagement system 300 of FIG. 3. Turning to FIG. 6, the photovoltaicdevice 200 can represent any number of photovoltaic devices such as thesolar cell 100 and/or the solar panels 10 as illustrated. As shown, thesolar panels 10 are wired in parallel, but can also be wired in seriesand any combination thereof.

A voltage pulser 60, such as a high voltage pulse generator, can apply atime varying voltage pulse 71 (shown in FIG. 7) across one or more ofthe solar panels 10. In one embodiment, a duration D_(P) of the voltagepulse 71 can be short—nominally 10-2000 ns—and a magnitude can behigh—nominally 100-500+ Volts. In the embodiment shown in FIG. 6, thevoltages applied, the pulse width, and the pulse repetition rate arefixed at a predetermined level to provide optimum performance underselected operating conditions. For example, with reference to FIGS. 6and 7, the voltage pulse 71 has the duration D_(P) of about 1000 ns,which voltage pulse 71 is repeated with a period of 1/f. The durationD_(P) of the voltage pulse 71 and the frequency f of the voltage pulse71 are chosen such that the reactance of inductors in the voltageinverter 31 present a high impedance to the voltage pulser 60, whichhigh impedance allows a high voltage to be developed across theelectrodes 101 a, 101 b (shown in FIG. 1) of the solar panels 10 and notbe shorted out by the inverter 31.

Additionally, series inductors (not shown) can be placed at the input ofthe inverter 31, which series inductors are capable of handling thecurrent input to the inverter 31 and act as an RF choke such that thevoltage pulses 71 are not attenuated (or effectively shorted) by theresistive component of the inverter 31. The duty cycle (time the pulseis on/time the pulse is off) can be nominally 0.1-10%.

The strength of the electric field 250 imposed on the photovoltaicdevice 200 is a function of the construction of the photovoltaic device200, such as the thickness of the photovoltaic device 200, the materialand dielectric constant of the photovoltaic device 200, the maximumbreakdown voltage of the photovoltaic device 200, and so on.

For the voltage pulse 71 shown in FIG. 7, a Fourier analysis of thiswaveform results in a series of pulses with frequencies ω=nω_(o) whereω_(o)=2πf and the strength of the pulses is given by Equation 4:

$\begin{matrix}{{V(\omega)} = {2{\pi\tau}\; V_{App}{\sum\limits_{n = {- \infty}}^{\infty}\frac{\sin\; n\;{\pi\tau}}{n\;{\pi\tau}}}}} & ( {{Equation}\mspace{20mu} 4} )\end{matrix}$

In Equation 4, n is a series of integers from −∞ to +∞. Accordingly, the0th order pulse (i.e., n=0) has a DC component that is shorted throughthe resistive load R_(L). The first order of the voltage pulse 71applied across the solar panels 10 is V_(App) (1−D_(P)/f), where D_(P)/fis the duty cycle of the pulse, D_(P) is the pulse duration, and f isthe repetition rate of the pulse. Since the inductance of the inverter31 acts as a high impedance Z to the voltage pulse 71 generated by theembodiment of FIG. 6, a high voltage pulse 71 is developed across eachof the solar panels 10, which, in turn, creates a high electric field250 across the solar panels 10.

As shown in FIG. 6, the voltage inverter 31 represents the external loadR_(L). However, the external load R_(L) can include purely resistivecomponents such that a set of inductors can be placed in series with theload R_(L) to act as the RF choke so that the voltage pulse 71 (and theelectric field 250) is applied across the solar panels 10.

Any number of circuits can be used in the voltage pulser 60 to apply thevoltage pulse 71 as desired. One such exemplary circuit used in thevoltage pulser 60 is shown in FIG. 8. As illustrated, the voltage pulser60 includes a pulse generator 61 (not shown), a high voltage source 69(not shown), and a switching transistor 68 for impressing the highvoltage pulse 71 on the solar panels 10 (e.g., by switching the outputof the high voltage source 69 to the solar panels 10) shown in FIG. 6.The voltage pulser 60 of FIG. 8 contains a device that transferselectrical signals between two, electrically isolated, circuits usinglight, such as an opto-isolator 62 to isolate the pulse generator 61from the high voltage switching transistor 68. Advantageously, theopto-isolator 62 prevents a high voltage (e.g., from the high voltagesource 69) from affecting the pulse signal 71. The opto-isolator circuit62 is illustrated with pins 1-8 and is shown as part of the inputcircuit to the voltage pulser 60.

A bias voltage supply 63 (not shown) provides voltage (e.g., 15 VDC) tothe opto-isolator 62 to supply the required bias for the opto-isolator62. A capacitor 64 isolates the bias voltage supply 63, creating an ACpath for any signal from distorting the bias supply to the opto-isolator62. Pins 6 and 7 of the opto-isolator 62 are the switching signal outputof the opto-isolator 62 used to drive the high voltage switchingtransistor 68. A diode 66—such as a Zener diode—is used to hold theswitching threshold of the switching transistor 68 to above the setpoint of the diode 66, eliminating any noise from inadvertentlytriggering the switching transistor 68. Resistor 67 sets the bias pointfor the gate G and emitter E of the switching transistor 68. When thevoltage applied across pins 6 and 7 of the opto-isolator 62 exceeds thethreshold set by the resistor 67, the switching transistor 68 is turned“on” and current flows between the collector C and the emitter E of thehigh voltage switching transistor 68. Accordingly, the high voltageswitching transistor 68 presents an Injected High Voltage source to thesolar panels 10 until the Control Pulse IN from the pulse generator 61drops below the set threshold on the G of the high voltage switchingtransistor 68, which stops the current flow across C-G shutting theswitching transistor 68 “off.”

As in the previous embodiments described above, application of theelectric field 250 to the solar panels 10 can increase the current andpower output of the solar panels 10 when subsequently connected to theinverter 31 by a predetermined amount (e.g., dependent upon theintensity of light incident on solar panels 10, the voltage appliedV_(APP) to the solar panels 10 by the voltage source 50, the thicknessof the solar panels 10, the pulse width D_(P), and the frequency f thatthe voltage pulse 71 is applied to the solar panels 10, and so on).Similarly, under high intensity light conditions, the improvement inpower output of the solar panels 10 can be on the order of 20%; andunder low light conditions can be 50+%.

The improvement in the performance of the photovoltaic device 200cooperating with the electric field 250 can be measured as an increasein the short circuit current of the solar cell, I_(sc), as shown inEquation 5:

I _(sc) =I _(Base)[1+c(V(τ,f),t,ε)*(p _(max) −p)]  (Equation 5)

where I_(Base) is the short circuit current when no external electricfield 250 is applied and p_(max) is the maximum optical power wherebyany additional power does not create any additional electron-hole pairs.As the improvement in the current output of the solar cell is driven bythe electric field 250, the form of c(V(τ,f),t,ε) can be described byEquation 6:

c(V(τ,f),t,ε)=m(t,ε)V _(App)*(1−exp(τ/τ_(o)))*exp(−f _(decay)/f)  (Equation 6)

In Equation 6, m(t, ε) is dependent on the photovoltaic device 200. Theimprovement in the short circuit current I_(sc) due to the electricfield 250 can be linear with respect to the applied voltage V_(App). Theimprovement observed with respect to the pulse repetition rate has acharacteristic decay rate of (1/f_(decay)) and to behave exponentiallywith respect to the pulse rate f. The improvement observed with respectto the pulse width τ can also behave exponentially and describe howquickly the applied voltage V_(App), reaches full magnitude. Theimprovement observed with respect to the pulse width τ is dependent uponthe details of the voltage pulser 60. The increase in the short circuitcurrent I_(sc), as a function of applied voltage V_(App), the pulserepetition rate f, and the pulse width τ, are shown in FIGS. 11A-C,respectively.

FIG. 11A shows the expected improvement in the short circuit currentI_(sc), for the solar panel 10 (shown in FIG. 2) as a function of themagnitude of the applied voltage pulse V_(App). As shown, the pulsewidth and the pulse repetition rate are fixed, and the magnitude of thepulse voltage is varied from 50 to 250 volts. The improvement in theshort circuit current ΔI_(SC) increases from nominally 0.1 to 2 Amps.The change in the short circuit current ΔI_(SC) as a function of theapplied voltage pulse V_(APP) is, to first order, approximately linear.FIG. 11B shows the change in the improvement of the short circuitcurrent ΔI_(SC) as a function of the pulse repetition rate for a fixedpulse width and a fixed voltage pulse. As shown in FIG. 11B, theimprovement in the short circuit current ΔI_(SC) decreases fromapproximately 1.7 amps to about 0.45 amps as the pulse repetition rateincreases from 10 to 100 in arbitrary time units. This behavior isapproximately exponential. FIG. 11C shows the change in the improvementof the short circuit current ΔI_(SC) as a function of the pulse widthfor a fixed pulse repetition rate and a fixed voltage pulse. For thisexample, the improvement of the short circuit current, ΔI_(SC) increasesfrom 0 to 1.2 amperes as the pulse width increases from 0 to 2000 overtime.

In each of the described embodiments, increasing the strength of theelectric field 250 across the electrodes 101 a, 101 b of the solar cell100 or solar panel 10 increases the efficiency of the solar cell 100 orpanel 10, for example, up to a maximum electric field strength ofE_(max). Stated another way, once the strength of the electric field 250reaches a maximum strength, the electron-hole recombination rate hasbeen minimized. Accordingly, it can be advantageous to configure thecontrol circuit of the photovoltaic device 200 to maximize the outputcurrent and voltage under varying operating conditions.

For example, turning to FIG. 9A, a current sensor 33 and a voltage probe32 are shown coupled to the solar cell management system 300 of FIG. 4.As illustrated, the current sensor 33 is coupled in series between thesolar panel 10 and the inverter 31. The current sensor 33 can monitorthe current output of the solar panel 10. Similarly, the voltage probe32 is connected across the solar panels 10 and the inverter 31 tomonitor the output voltage of the solar panel 10.

A control circuit 35 is coupled to both of the current sensor 33 viacontrol leads 33 a and the voltage probe 32 via control leads 32 a. Thecurrent sensor 33 can be an inline or inductive measuring unit andmeasures the current output of the solar panels 10. Similarly, thevoltage sensor 32 is used to measure the voltage output of the solarpanels 10. The product of the current measured from the current sensor33 and the voltage measured from the voltage probe 32 is the poweroutput from the solar panels 10 to the inverter 31.

In some embodiments, the voltage probe 32 may also serve as a powersource for the control circuit 35 and is active only as long as thesolar panels 10 are illuminated and provide sufficient power to activatecontrol circuit 35. The control circuit 35 further is coupled to theswitch 55 to determine switching times and frequency discussed withreference to FIG. 4. The duration of the switching times and thefrequency can be controlled to apply the voltage V_(App) across thesolar panels 10 such that both the current generated within the solarcell 100 and measured by the current sensor 33 and voltage probe 32 aremaximized under various operating conditions, such as under differing orvariable lighting conditions.

In one embodiment for applying the electric field 250, the solar panel10 initially does not generate power, for example, during the night orheavy cloud coverage. As the solar panels 10 are illuminated (forexample, during the morning), voltage and current are generated by thesolar panels 10, and the leads 32 a begin to deliver both current andvoltage to the control circuit 35. The control circuit 35 contains a lowvoltage logic power supply (not shown) to drive control logic within thecontrol circuit 35. The control circuit 35 also includes the powersource 50 for providing a high voltage power supply. The voltage source50 has a variable output which can be adjusted by the control circuit 35and is responsible for placing V_(App) on a lead 38. The high voltageoutput V_(App) from the control circuit 35 drives the lead 38 and isconnected to the switch 55. The lead 38 is used to apply voltage V_(App)through the switch 55 to the solar panels 10. In this example, thecontrol circuit 35 is configured not to apply any voltage V_(App) to thesolar panels 10 until enough power is generated by the solar panels 10to activate both the low voltage logic power supply and the high voltagepower supply.

In an alternative embodiment, the control circuit 35 can be configuredto apply the electric field 250 and maximize the power output as theillumination in the day increases and decreases. The control circuit 35can provide the electric field 250 and stabilize the power output of thesolar panels 10 according to any method described above, includingprocess 9000 shown in FIG. 9B.

Turning to FIG. 9B, the process 9000 includes initializing power, atstep 900. Enough power must be present from the output of the solarpanels 10 to activate both the low voltage logic power supply, whichoperates the control logic in control circuit 35, and the high voltagepower supply necessary to place a high voltage on the lead 38 andthrough the switch 55. Alternatively, the control circuit 35 can bepowered from an external source (not shown)—for example, a battery, alarge capacitor, an external AC power supply—which allows the lowvoltage logic power supply to operate and the control circuit 35 tomonitor the power output of the solar panels 10 until the solar panels10 generate enough power output to warrant applying the electric field250 on the solar panels 10 to augment their power output. Since thecontrol circuit 35 is starting up, all of the parameters (e.g., theapplied high voltage V_(App), the switch duration time D, and theswitching frequency f) are initialized. In one embodiment, the appliedhigh voltage V_(App) is set to zero while the switching duration D andthe switching frequency f are set to nominal values of D=τ_(o) andf=f_(o). All of the control indices, n, i, and j are initialized tozero.

The control circuit 35 then determines, at step 901, whether the voltageas measured on the voltage probe 32 is above or below a predeterminedminimum v_(min) and whether the current as measured on the currentsensor 33 is above a predetermined minimum, i_(min). The combination ofv_(min) and i_(min) have been chosen such that the solar panels 10 aredetermined to be illuminated and generating some nominal percentage, forexample, 5%, of their average rated power and that there is enough powerbeing generated to supply the power source 50 within the control circuit35 to augment the output of the solar panels 10. If the control circuit35 determines that both the measured current and voltage are above therespective predetermined minimums, the control circuit 35 is nowoperational and process 9000 moves to step 903; otherwise, the process9000 goes into a wait state, at step 902, and returns to step 900.

In step 903, the control circuit 35 measures the current flowing intothe inverter 31 via the current sensor 33, the voltage across theinverter 31 via the voltage sensor 32, and calculates the power(nominally, current×voltage) flowing through the inverter 31. A controlindex n is incremented to n+1.

In step 904, the control circuit 35 compares V_(App) with V_(max).V_(max) can be a preset value and represents the maximum voltage thatcan be placed on the solar panels 10 without damaging either the solarpanels 10 or the inverter 31. Depending upon the type of the solar panel10, V_(max) is typically between 600 V and 1,000 V. If V_(App) is lessthan V_(max), then process 9000 proceeds to step 906; otherwise, process9000 waits in step 905.

In step 906, the control circuit 35 increments the applied high voltageV_(App) by an amount nΔV and activates the switch 55. Activating theswitch 55 disconnects the solar panels 10 from the inverter 31 andconnects the solar panels 10 to V_(App) from the control circuit 35 onleads 38. For this example, ΔV can be a fixed voltage step of 25 Voltsalthough larger or smaller voltage steps can be used. The voltageV_(App) imposes the electric field 250 on the solar panels 10 such thatthe strength of the electric field 250 is proportional to the appliedvoltage V_(App). The duration of the connection of the solar panels 10to V_(App) within the control circuit 35 is chosen to not interruptoperation of the inverter 31. For this example, the duty cycle is chosento be 5% (the solar panels 10 are connected 5% of the time to V_(App)within the control circuit 35) and the default duration of the switchingtime is chosen to be nominally 1000 ns. Alternative switching times canbe used as desired. The control circuit 35 again receives themeasurement of the current flowing into the inverter 31 via the currentsensor 33, receives the measurement of the voltage across the inverter31 via the voltage sensor 32, and recalculates the power flowing throughthe inverter 31.

In step 908, the control circuit 35 compares the power output of thesolar panels 10 before V_(App) was placed on the solar panel 10 to themost recent measurement. If the power has increased, the process 9000returns to step 901 and is repeated. The voltage applied on the lead 38is increased by ΔV until either the applied high voltage V_(App) isgreater than V_(max) or until the increase in the applied high voltageV_(App) does not yield an increase in output power of the solar panels10. V_(max) is defined here as the maximum voltage that can be placed ona solar panel without causing it any damage. Depending upon the type ofthe solar panel 10, V_(max) is typically approximately 600 to 1,000 V.In both cases, process 9000 waits in step 905. The duration of the waitstate could be from seconds to minutes.

After the wait step 905, process 9000 continues to step 907. If thepower, as measured through the leads 32 a and 33 a, has not changed, theindex n is decremented (n=n−1), the applied voltage V_(App) on the leads38 to the solar panel(s) 10 is decreased by the amount ΔV, and thecontrol circuit 35 activates the switch 55. Process 9000 continues instep 909 where the power output is measured by the current sensor 33 andvoltage probe 32. If the power output shows a drop, process 9000continues to step 910. If the power output has increased, the process9000 returns to step 907 and the applied voltage V_(App) continues todecrement until the power output of the solar panels 10 ceases todiminish. The process 9000 proceeds to step 910.

In step 910, the control circuit 35 increases the duration that theswitch 55 is connected to the solar panels 10 on the lead 38 in thefirst position discussed above. The amount of time that the switch 55 isconnected to the voltage source 50 is increased by an amount iΔτ_(o).The switch 55 is activated and the power output of the solar panels 10is again monitored by the current sensor 33 and the voltage probe 34.The process 9000 proceeds to state 912 to determine whether the poweroutput of the solar panels 10 increases. If so, process 9000 moves tostep 910 and the duration that the solar panels 10 are connected to thevoltage source 50 is increased again. The switching duration willincrease until the output power of the solar panels 10 reaches a maximum(or until a fixed duration limit—for example, 3-5 μseconds isreached)—at which point the switch duration changes driven by thecontrol circuit 35 stops. However, if at step 912, the control circuit35 determines that increasing the switch duration D causes a decrease inthe power output as measured by the current sensor 33 and the voltageprobe 32, process 9000 continues to step 911 and the switch duration Dis decreased by iterating between steps 911 and 913 until the poweroutput of the solar panels 10 is maximized again. After the controlcircuit 35 has determined that the switching duration has been optimizedfor maximum output power of solar panels 10 by repeating step 910 tostep 913, process 9000 continues to step 914.

In step 914, the control circuit 35 begins to increase the frequency ofconnection f at which the switch 55 is connected to the control circuit35. The frequency f that the switch 55 is connected to the voltagesource 50 is increased by jΔf from the original switching frequencyf_(o) such that f=f_(o)+jΔf. In step 914, the switch 55 is connectedbetween the lead 38 and the solar panels 10 at a new frequency, f, andthe power output of the solar panels 10 is again monitored by thecurrent sensor 33 and the voltage probe 34. The process 9000 continuesto step 916. If the power output of the solar panels 10 has increased,the process 9000 moves back to step 914 and the rate at which the solarpanels 10 are connected to the voltage source 50 is increased again. Therate of connection will increase until the output power of the solarpanels 10 reaches a maximum or until a maximum frequency f_(max), atwhich point the process 9000 moves to step 915. In step 914, thefrequency the switch 55 connects to the high voltage 50 on the lead 38is now decremented by an amount jΔf and the switch 55 is activated againand the power output of the solar panels 10 is again monitored by thecurrent sensor 33 and the voltage probe 32. At that point, the controlcircuit 35 decides whether the decrease in the rate of connectionincreases the power output of solar panels 10 in step 917. If so, theprocess 9000 returns to step 915. Alternatively, if the frequency ofswitching reaches some minimum frequency f_(min), the process 9000 movesto step 918 to wait.

In step 918, once the power output of the solar panels 10 has beenmaximized, the control circuit 35 goes into a wait state for a period oftime. The period of wait time can be seconds or minutes. After waitingin step 918, the process 9000 moves to step 901 where process 9000 againbegins to vary the voltage, the switch connection time and the switchingrate from the previous optimized values to validate the solar panels 10are still operating at their maximum output levels. The applied voltage50 from the control circuit 35, the switching duration, and theswitching rate are all varied over the course of operation during a dayto be sure that the solar panels 10 are operating under with maximumoutput power under the operational conditions of that particular day.

If at step 901, the voltage as measured on voltage sensor 32 drops belowthe predetermined minimum v_(min), and the current as measured oncurrent sensor 33 drops below a predetermined minimum i_(min), thecontrol circuit 35 will remove any voltage on lines 38, and the controlcircuit 35 will move to step 902 to wait before returning to step 900(where the system will reinitialize all of the parameters and indices).Process 9000 will alternate from step 900 to 901 to 902 to 900 untilboth the voltage as measured on the voltage probe 32 and the current asmeasured on the current sensor 33 are both above v_(min) and i_(min)respectively, at which point the process 9000 will move from step 901 tostep 903.

Different state machines within control circuit 35 can be implemented toyield similar results and are covered by this disclosure. However, theprocess 9000 described above advantageously minimizes the magnitude ofthe applied voltage V_(App) to the lowest value possible such that theproduct of the current measured by the current probe 33 and the voltagemeasured by the voltage probe 32 are maximized. The applied voltageV_(App) is dithered—that is changed by small amounts both up anddown—over the course of operation in a day to account for changes theincident optical power, p, on the solar cell 100, the solar panel 10, orthe plurality of solar panels 10 over the course of a day so that themaximum power output can always be maintained.

Most of the steps described in process 9000 above were designed toaddress adiabatic changes in illumination that occur slowly over periodsof multiple minutes or hours. In an alternative embodiment, if theillumination variances were to occur at a higher rate of change, theprocess 9000 can be adapted to minimize the high frequency variations inDC power output to the inverter by attempting to hold the DC outputpower from varying at too high a rate of change, hence making thequality of the inverter higher.

In another example, turning to FIG. 10A, the current sensor 33 and thevoltage probe 32 are shown coupled to the solar cell management system300 of FIG. 6. As illustrated, the current sensor 33 is coupled inseries between the solar panel 10 and the inverter 31. The currentsensor 33 can monitor the current output of the solar panel 10.Similarly, the voltage probe 32 is connected across the solar panels 10and the inverter 31 to monitor the output voltage of the solar panel 10.

A control circuit 36 is coupled to both the current sensor 33 viacontrol leads 33 a and the voltage probe 32 via control leads 32 a. Thecurrent sensor 33 can be an inline or inductive measuring unit andmeasures the current output of the solar panels 10. Similarly, thevoltage sensor 32 is used to measure the voltage output of the solarpanels 10. The product of the current measured from the current sensor33 and the voltage measured from the voltage probe 32 allow for acalculation of the power output from the solar panels 10 to the inverter31.

In some embodiments, the voltage probe 32 may also serve as a powersource for the control circuit 36 and is active only as long as thesolar panels 10 are illuminated and provide sufficient power to activatecontrol circuit 36. The control circuit 36 further is coupled to voltagepulser 60 to control the amplitude of the voltage pulse V_(App), thepulse duration D_(P) and the pulse frequency f discussed with referenceto FIG. 6. The pulse duration D_(P), the pulse frequency f, and thepulse voltage V_(App) applied across the solar panels 10 can becontrolled and adjusted such that both the current generated within thesolar panel 10 and measured by the current sensor 33 and voltage probe32 are maximized under various operating conditions, such as underdiffering or variable lighting conditions.

In one embodiment for applying the electric field 250, the solar panel10 initially does not generate power, for example, during the night orheavy cloud coverage. As the solar panels are illuminated (for example,during the morning), voltage and current are generated by the solarpanels 10, and the leads 32 a begin to deliver both current and voltageto the control circuit 36. The control circuit 36 contains a low voltagelogic power supply (not shown) to drive control logic within the controlcircuit 36. The pulser circuit 60 contains both a low voltage and highvoltage power supply (not shown). The high voltage power supply involtage pulser 60 has a variable output which can be adjusted by controlcircuit 36 and is responsible for placing V_(App) on solar panels 10. Inthis example, the control circuit 36 is configured not to apply anyvoltage to the solar panels 10 until enough power is being generated bythe solar panels 10 to activate both the low voltage logic power supplyand the high voltage power supply in pulser 60.

In an alternative embodiment, the control circuit 36 is configured tocontrol the electric field 250 and maximize the power output as theillumination in the day increases and decreases. The control circuit 36can control the electric field 250 applied by voltage pulser 60 andstabilize the power output of the solar panels 10 according to anymethod described above, including process 10000 shown in FIG. 10B.

Turning to FIG. 10B, the process 10000 includes initializing power, atstep 1000. Enough power must be present from the output of the solarpanels 10 to activate both the low voltage logic power supply, whichoperates the control logic in control circuit 36, and the low and highvoltage power supply in voltage pulser 60. Alternatively, the controlcircuit 36 can be powered from an external source (not shown)—forexample, a battery, a large capacitor, an external AC power supply—whichallows the low voltage logic power supply to operate and the controlcircuit 36 to monitor the power output of the solar panels 10 until theyhave enough power output to warrant applying the electric field 250 onthe solar panels 10 to augment their power output. Since the controlcircuit 36 is starting up, all of the parameters (e.g., applied highvoltage V_(App), the pulse duration D_(P), and the pulse repetitionfrequency, f) are initialized. In one embodiment, the applied highvoltage V_(App) is set to zero while the pulse duration D_(P) and pulserepetition rate f are set to nominal values of D_(P)=τ_(o) and f=f_(o).All of the control indices, n, i, and j are initialized to zero.

The control circuit 36 then determines in step 1001 whether the voltageas measured on the voltage probe 32 is above or below a predeterminedminimum v_(min) and whether the current as measured on the currentsensor 33 is above a predetermined minimum, i_(min). The combination ofv_(min) and i_(min) have been chosen such that the solar panels 10 aredetermined to be illuminated and generating some nominal percentage, forexample, 5%, of their average rated power and that there is enough powerbeing generated to supply the high voltage power supply to augment theoutput of the solar panels 10. If the control circuit 36 determines thatboth the measured current and voltage are above the respectivepredetermined minimums, then process 10000 is now operational and movesto step 1003; if not, process 10000 goes into a wait state 1002 andreturns to step 1000.

In step 1003, the control circuit 36 measures the current flowing intothe inverter 31 via the current sensor 33, the voltage across theinverter 31 via the voltage sensor 32, and calculates the power flowingthrough the inverter 31 (nominally, I×V). A control index n isincremented to n+1.

In step 1004, process 10000 compares V_(App) with V_(max). V_(max) is apreset value and represents the maximum voltage that can be placed onthe panels without damaging either the panels 10 or the inverter 31. IfV_(App) is less than V_(max), then process 10000 proceeds to step 1006;otherwise, process 10000 waits in step 1005.

In step 1006, the control circuit 36 signals the voltage pulser 60 toincrement the applied high voltage V_(App) by an amount nΔV and signalsthe voltage pulser 60 to apply the voltage pulse to the solar panels 10.For this example, ΔV can be a fixed voltage step of 25 Volts, althoughlarger or smaller voltage steps can be used. The voltage V_(App) imposesthe electric field 250 on the solar panels 10 and the strength of theelectric field 250 is proportional to the applied voltage V_(App). Forthis example, the pulse width D_(P) is chosen to be 1000 ns and thepulse repetition rate is chosen to be 20 μseconds. Other pulse widthsand pulse repetition rates could also be chosen. The control circuit 36again receives the measurement of the current flowing into the inverter31 via the current sensor 33, receives the measurement of the voltageacross the inverter 31 via the voltage sensor 32, and recalculates thepower flowing through the inverter 31.

In step 1008, the control circuit 36 compares the power output of thesolar panels 10 before V_(App) was placed on the solar panel 10 to themost recent measurement. If the power has increased, process 10000returns to step 1001 and is repeated. The applied voltage V_(App) isincreased by ΔV until either the applied high voltage V_(App) is greaterthan V_(max) or until the increase in the applied high voltage V_(App)does not yield an increase in output power of the solar panels 10.Again, V_(max) is defined here as the maximum voltage that can be placedon a solar panel 10 without causing it any damage and depending uponsolar panel type, it would typically be approximately 600 to 1,000 V. Inboth cases, process 10000 waits in step 1005. The duration of the waitstate could be from seconds to minutes.

After the wait step 1005, process 10000 enters step 1007. If the power,as measured through the leads 32 a and 33 a, has not changed, index n isdecremented (n=n−1), the applied voltage pulse V_(App) is decreased bythe amount ΔV, and the control circuit 36 activates the pulser 60.Process 10000 continues in step 1009 where the power output as measuredby the current sensor 33 and voltage probe 32. If the power output showsa drop, process 10000 continues to step 1010. If the power output hasincreased, process 10000 returns to step 1007 and the applied voltageV_(App) continues to decrement until the power output of the solarpanels 10 ceases to diminish. The process 10000 proceeds to step 1010.

In step 1010, the control circuit 36 begins to increase the durationD_(P) of the voltage pulse. The voltage pulse duration D_(P) isincreased by an amount iΔτ_(o). The voltage pulser 60 is activated andthe power output of the solar panels 10 is again monitored by thecurrent sensor 33 and the voltage probe 34. The process 10000 proceedsto state 1012 to determine whether the power output of the solar panels10 increases. If so, process 10000 moves to step 1010 and the durationD_(P) of the voltage pulse 71 is increased again. The pulse durationD_(P) will increase until the output power of the solar panels 10reaches a maximum or until a fixed duration limit—for example, a pulseduration of 5 μseconds is reached—at which point the pulse width changesdriven by the control circuit 36 stops. However, if at step 1012, it isfound that the increasing the pulse width causes a decrease in the poweroutput as measured by the current sensor 33 and the voltage probe 32,process 10000 continues to step 1011. The pulse width is decreased byiterating between steps 1011 and 1013 until the power output of thesolar panels 10 is maximized again. After the control circuit 36 hasdetermined that the pulse duration has been optimized for maximum outputpower of solar panels 10 by going through step 1010 to step 1013, theprocess continues to step 1014.

In step 1014, the control circuit 36 increases the frequency of thevoltage pulses. The frequency of the voltage pulses is increased by jΔffrom the original switching frequency f_(o) such that f=f_(o)+jΔf. Instep 1014, voltage pulses are applied by the voltage pulser 60 to thesolar panels 10 at a new frequency f, and the power output of the solarpanels 10 is again monitored by the current sensor 33 and the voltageprobe 34. The process 10000 then moves to step 1016.

If the power output of the solar panels 10 has increased, the process10000 moves back to step 1014 and the rate at which voltage pulses areapplied to the solar panels 10 is increased again. The increase in therate of voltage pulses will increase until the output power of the solarpanels 10 reaches a maximum or until a maximum frequency f_(max), atwhich point the process 10000 moves to step 1015. In step 1014, thefrequency of the voltage pulses is now decremented by an amount jΔf andthe voltage pulser 60 switch is activated again and the power output ofthe solar panels 10 is again monitored by the current sensor 33 and thevoltage probe 32. At that point, the control circuit 36 determineswhether the decrease in the rate of voltage pulses increases the poweroutput of solar panels 10 in step 1017. If so, the process 10000 returnsto step 1015. Alternatively, if the frequency of switching reaches someminimum frequency f_(min), the process 10000 moves to step 1018, whichis a wait state.

In step 1018, once the power output of the solar panels 10 has beenmaximized, process 10000 goes into a wait state for a period of time.The period of wait time can be seconds or minutes. After waiting in step1018, the process 10000 moves to step 1001 where the control circuit 36again begins to vary the pulse voltage, the pulse duration, and thepulse repetition rate from the previous optimized values to validate thesolar panels 10 are still operating at their maximum output levels. Thepulse amplitude V_(App), the pulse duration, and the pulse repetitionrate are all varied over the course of operation during a day to be surethat the solar panels 10 are operating under with maximum output powerunder the operational conditions of that particular day.

If at step 1001, the voltage as measured on the voltage sensor 32 dropsbelow the predetermined minimum v_(min), and the current as measured oncurrent sensor 33 drops below a predetermined minimum i_(min), thecontrol circuit 36 will stop the voltage pulser 60 and the process 10000will move to step 1002 wait state and then to step 1000 where the systemwill reinitialize all of the parameters and indices. The process 10000will move from step 1000 to 1001 to 1002 to 1000 until both the voltageas measured on the voltage probe 32 and the current as measured on thecurrent sensor 33 are both above v_(min) and i_(min) respectively, atwhich point process 10000 will move from step 1001 to step 1003.

Different state machines within the control circuit 36 can beimplemented to yield similar results and are covered by this disclosure.However, the process 10000 described above advantageously minimizes themagnitude of the applied voltage pulse V_(App) to the lowest valuepossible such that the product of the current measured by the currentprobe 33 and the voltage measured by the voltage probe 32 are maximized.The applied voltage pulse V_(App) is dithered—that is changed by smallamounts both up and down—over the course of operation in a day toaccount for changes the incident optical power, p, on the solar cell100, the solar panel 10, or the plurality of solar panels 10 over thecourse of a day so that the maximum power output can always bemaintained.

The steps described in process 10000 can address adiabatic changes inillumination that occur slowly over periods of multiple minutes orhours. In an alternative embodiment, if the illumination variances wereto occur at a higher rate of change, the process 10000 can be adapted tominimize the high frequency variations in DC power output to theinverter by attempting to hold the DC output power from varying at toohigh a rate of change, hence making the quality of the inverter higher.

In selected embodiments, one or more of the features disclosed hereincan be provided as a computer program product being encoded on one ormore non-transitory machine-readable storage media. As used herein, aphrase in the form of at least one of A, B, C and D herein is to beconstrued as meaning one or more of A, one or more of B, one or more ofC and/or one or more of D. Likewise, a phrase in the form of A, B, C orD as used herein is to be construed as meaning A or B or C or D. Forexample, a phrase in the form of A, B, C or a combination thereof is tobe construed as meaning A or B or C or any combination of A, B and/or C.

The described embodiments are susceptible to various modifications andalternative forms, and specific examples thereof have been shown by wayof example in the drawings and are herein described in detail. It shouldbe understood, however, that the described embodiments are not to belimited to the particular forms or methods disclosed, but to thecontrary, the present disclosure is to cover all modifications,equivalents, and alternatives.

What is claimed is:
 1. A system for increasing solar cell efficiency,comprising: a voltage pulse generation circuit for applying one or morevoltage pulses with a positive magnitude to an output power electrode ofa solar cell to adjust an output power or an output current supplied bythe solar cell via the output power electrode.
 2. The system of claim 1,wherein said voltage pulse generation circuit applies the voltage pulsesacross a pair of output power electrodes of the solar cell, the outputpower or the output current being supplied via the pair of output powerelectrodes.
 3. The system of claim 1, wherein application of the voltagepulses to the output power electrode generates an electric field at thesolar cell.
 4. The system of claim 3, wherein the electric field isgenerated in a first direction being in a same direction as a polarityof the output power electrode for increasing the output power or theoutput current supplied by the solar cell.
 5. The system of claim 4,wherein the electric field generated in the first direction acceleratesa mobility of an electron and a hole of at least one first electron-holepair in the solar cell.
 6. The system of claim 3, wherein the electricfield is generated in a second direction being in an opposite directionof as a polarity of the output power electrode for decreasing the outputpower or the output current supplied by the solar cell.
 7. The system ofclaim 6, wherein the electric field generated in the second directiondecreases a mobility of an electron and a hole of at least one secondelectron-hole pair in the solar cell.
 8. The system of claim 1, whereinthe voltage pulses have a uniform positive magnitude.
 9. The system ofclaim 1, wherein the voltage pulses have an amplitude within anamplitude range between 100 Volts and 500 Volts, a frequency within afrequency range between 20 KHz and 200 KHz, a period within a periodrange between 5 microseconds and 50 microseconds, a nominal duty cyclein a duty cycle range between 0.1% and 10% or a combination thereof. 10.The system of claim 1, wherein said voltage pulse generation circuitcomprises a switching circuit for applying a supplied voltage signal tothe output power electrode as the voltage pulses.
 11. The system ofclaim 10, wherein said switching circuit comprises a switchingtransistor.
 12. The system of claim 10, wherein the supplied voltagesignal comprises a constant voltage signal.
 13. The system of claim 10,wherein said voltage pulse generation circuit includes a voltage sourcecircuit for supplying the supplied voltage signal.
 14. The system ofclaim 13, wherein said switching circuit is at least partiallyintegrated with said voltage source circuit.
 15. The system of claim 10,wherein said switching circuit is configured to apply the suppliedvoltage signal to the output power electrode as the voltage pulses byalternating between a first switching mode for closing a current pathbetween said voltage source circuit and the output power electrode and asecond switching mode for opening the current path.
 16. The system ofclaim 15, further comprising a pulse generator circuit for providing acontrol signal to a control electrode of said switching circuit toalternate said switching circuit between the first and second switchingmodes.
 17. The system of claim 15, further comprising a control circuitfor adjusting a switching frequency between the first switching mode andthe second switching mode, a first duration of the first switching mode,a second duration of the second switching mode, a duty cycle of thefirst switching mode and the second switching mode, a first repetitionrate of the first switching mode, a second repetition rate of the secondswitching mode or a combination thereof.
 18. The system of claim 17,wherein said control circuit adjusts the switching frequency to bewithin a frequency range between 20 KHz and 200 KHz, the first durationto be in a first duration range between 10 nanoseconds and 2000nanoseconds, the second duration to be in a second duration rangebetween 10 nanoseconds and 2000 nanoseconds, the duty cycle of thevoltage pulses to be within a duty cycle range between 0.1% and 10% or acombination thereof.
 19. The system of claim 17, wherein said controlcircuit is at least partially integrated with said voltage sourcecircuit, said switching circuit or both.
 20. The system of claim 1,wherein said voltage pulse generation circuit is electrically isolatedfrom the output power electrode in the radio frequency domain.
 21. Thesystem of claim 1, further comprising a control circuit for adjusting afrequency of the voltage pulses, the magnitude of the voltage pulses, aperiod of the voltage pulses, a repetition rate of the voltage pulses, aduty cycle of the voltage pulses, a duration of the voltage pulses or acombination thereof.
 22. The system of claim 21, wherein said controlcircuit adjusts the frequency to be within a frequency range between 20KHz and 200 KHz, the magnitude to be within an amplitude range between100 Volts and 500 Volts, the period to be within a period range between5 microseconds and 50 microseconds, the duty cycle to be within a dutycycle range between 0.1% and 10%, the duration to be in a duration rangebetween 10 nanoseconds and 2000 nanoseconds or a combination thereof.23. The system of claim 21, further comprising a sensor system formonitoring the output power, the output current, an output voltage ofthe solar cell or a combination thereof, wherein said control circuitadjusts the frequency of the voltage pulses, the magnitude of thevoltage pulses, the period of the voltage pulses, the repetition rate ofthe voltage pulses, the duty cycle of the voltage pulses, the durationof the voltage pulses or a combination thereof based upon at least oneof the monitored output power, the monitored output current and themonitored output voltage.
 24. The system of claim 21, wherein saidcontrol circuit is at least partially integrated with said voltage pulsegeneration circuit.
 25. The system of claim 1, wherein the solar cell isconfigured to provide the output power or the output current to a loadvia the output power electrode.
 26. The system of claim 25, wherein theload converts the output power or the output current supplied by thesolar cell into an alternating current voltage or current.
 27. Thesystem of claim 25, further comprising an energy storage device formitigating voltage drop-out at the load during application of a selectedvoltage pulse to the output power electrode.
 28. The system of claim 27,wherein said energy storage device stores the output power or the outputcurrent supplied by the output power electrode as stored electricalenergy between adjacent voltage pulses and provides the storedelectrical energy to the load during application of the selected voltagepulse to the output power electrode.
 29. The system of claim 27, whereinsaid energy storage device comprises at least one inductor, at least onecapacitor, at least one battery or a combination thereof.
 30. The systemof claim 25, wherein said voltage pulse generation circuit iselectrically isolated from the load in the radio frequency domain. 31.The system of claim 1, wherein said voltage source applies the voltagepulses to at least one output power electrode of a plurality of solarcells to adjust a collective output power or a collective output currentsupplied by the solar cells via the output power electrode.
 32. Thesystem of claim 31, wherein the plurality of solar cells is disposed ina series device configuration, a parallel device configuration or acombination thereof.
 33. The system of claim 31, wherein the pluralityof solar cells comprise a solar panel.
 34. The system of claim 1,wherein application of the voltage pulses to the output power electrodeincreases the output power or the output current of the solar cell by upto fifty percent under low light conditions.
 35. The system of claim 1,wherein application of the voltage pulses to the output power electrodeincreases the output power or the output current of the solar cell bymore than fifty percent under low light conditions.
 36. The system ofclaim 1, wherein application of the voltage pulses to the output powerelectrode increases the output power or the output current of the solarcell by up to twenty percent under high intensity light conditions. 37.The system of claim 1, wherein application of the voltage pulses to theoutput power electrode increases the output power or the output currentof the solar cell between twenty percent and fifty percent.
 38. Thesystem of claim 1, wherein application of the voltage pulses to theoutput power electrode increases the output power or the output currentof the solar cell by more than fifty percent.
 39. The system of claim 1,wherein application of the voltage pulses to the output power electrodeaccelerates a mobility of an electron and a hole of at least one firstelectron-hole pair in the solar cell.
 40. The system of claim 1, whereinapplication of the voltage pulses to the output power electrode provideselectrons for filling at least one trap disposed between a valence bandof the solar cell and a conduction band of the solar cell.
 41. Thesystem of claim 1, wherein the output power or the output current isbased upon an intensity of light incident on the solar cell, the voltagepulses applied to the solar cell, a thickness of the solar cell, a pulsewidth of the voltage pulses, a frequency of the voltage pulses, or acombination thereof.
 42. The system of claim 1, wherein said voltagesource applies the voltage pulses to the solar cell without structuralmodification of the solar cell.
 43. A method for increasing solar cellefficiency, comprising: providing a voltage pulse generation circuit forapplying one or more voltage pulses with a positive magnitude to anoutput power electrode of a solar cell to adjust an output power or anoutput current supplied by the solar cell via the output powerelectrode.
 44. The method of claim 43, wherein the voltage pulsegeneration circuit applies the voltage pulses across a pair of outputpower electrodes of the solar cell, the output power or the outputcurrent being supplied via the pair of output power electrodes.
 45. Themethod of claim 43, wherein application of the voltage pulses to theoutput power electrode generates an electric field at the solar cell.46. The method of claim 45, wherein the electric field is generated in afirst direction being in a same direction as a polarity of the outputpower electrode for increasing the output power or the output currentsupplied by the solar cell.
 47. The method of claim 46, wherein theelectric field generated in the first direction accelerates a mobilityof an electron and a hole of at least one first electron-hole pair inthe solar cell.
 48. The method of claim 45, wherein the electric fieldis generated in a second direction being in an opposite direction of asa polarity of the output power electrode for decreasing the output poweror the output current supplied by the solar cell.
 49. The method ofclaim 48, wherein the electric field generated in the second directiondecreases a mobility of an electron and a hole of at least one secondelectron-hole pair in the solar cell.
 50. The method of claim 43,wherein the voltage pulses have a uniform positive magnitude.
 51. Themethod of claim 43, wherein the voltage pulses have an amplitude withinan amplitude range between 100 Volts and 500 Volts, a frequency within afrequency range between 20 KHz and 200 KHz, a period within a periodrange between 5 microseconds and 50 microseconds, a nominal duty cyclein a duty cycle range between 0.1% and 10% or a combination thereof. 52.The method of claim 43, wherein said providing the voltage pulsegeneration circuit comprises providing a switching circuit for applyinga supplied voltage signal to the output power electrode as the voltagepulses.
 53. The method of claim 52, wherein the switching circuitcomprises a switching transistor.
 54. The method of claim 52, whereinthe supplied voltage signal comprises a constant voltage signal.
 55. Themethod of claim 52, further comprising a voltage source circuit forsupplying the supplied voltage signal.
 56. The method of claim 55,wherein the switching circuit is at least partially integrated with thevoltage source circuit.
 57. The method of claim 52, wherein theswitching circuit is configured to apply the supplied voltage signal tothe output power electrode as the voltage pulses by alternating betweena first switching mode for closing a current path between the voltagesource circuit and the output power electrode and a second switchingmode for opening the current path.
 58. The method of claim 57, furthercomprising providing a pulse generator circuit for providing a controlsignal to a control electrode of the switching circuit to alternate theswitching circuit between the first and second switching modes.
 59. Themethod of claim 57, further comprising providing a control circuit foradjusting a switching frequency between the first switching mode and thesecond switching mode, a first duration of the first switching mode, asecond duration of the second switching mode, a duty cycle of the firstswitching mode and the second switching mode, a first repetition rate ofthe first switching mode, a second repetition rate of the secondswitching mode or a combination thereof.
 60. The method of claim 59,wherein the control circuit adjusts the switching frequency to be withina frequency range between 20 KHz and 200 KHz, the first duration to bein a first duration range between 10 nanoseconds and 2000 nanoseconds,the second duration to be in a second duration range between 10nanoseconds and 2000 nanoseconds, the duty cycle of the voltage pulsesto be within a duty cycle range between 0.1% and 10% or a combinationthereof.
 61. The method of claim 59, wherein the control circuit is atleast partially integrated with the voltage source circuit, theswitching circuit or both.
 62. The method of claim 43, wherein thevoltage pulse generation circuit is electrically isolated from theoutput power electrode in the radio frequency domain.
 63. The method ofclaim 43, further comprising providing a control circuit for adjusting afrequency of the voltage pulses, the magnitude of the voltage pulses, aperiod of the voltage pulses, a repetition rate of the voltage pulses, aduty cycle of the voltage pulses, a duration of the voltage pulses or acombination thereof.
 64. The method of claim 63, wherein the controlcircuit adjusts the frequency to be within a frequency range between 20KHz and 200 KHz, the magnitude to be within an amplitude range between100 Volts and 500 Volts, the period to be within a period range between5 microseconds and 50 microseconds, the duty cycle to be within a dutycycle range between 0.1% and 10%, the duration to be in a duration rangebetween 10 nanoseconds and 2000 nanoseconds or a combination thereof.65. The method of claim 63, further comprising providing a sensor systemfor monitoring the output power, the output current, an output voltageof the solar cell or a combination thereof, wherein the control circuitadjusts the frequency of the voltage pulses, the magnitude of thevoltage pulses, the period of the voltage pulses, the repetition rate ofthe voltage pulses, the duty cycle of the voltage pulses, the durationof the voltage pulses or a combination thereof based upon at least oneof the monitored output power, the monitored output current and themonitored output voltage.
 66. The method of claim 63, wherein thecontrol circuit is at least partially integrated with the voltage pulsegeneration circuit.
 67. The method of claim 43, wherein the solar cellis configured to provide the output power or the output current to aload via the output power electrode.
 68. The method of claim 67, whereinthe load converts the output power or the output current supplied by thesolar cell into an alternating current voltage or current.
 69. Themethod of claim 67, further comprising providing an energy storagedevice for mitigating voltage drop-out at the load during application ofa selected voltage pulse to the output power electrode.
 70. The methodof claim 69, wherein the energy storage device stores the output poweror the output current supplied by the output power electrode as storedelectrical energy between adjacent voltage pulses and provides thestored electrical energy to the load during application of the selectedvoltage pulse to the output power electrode.
 71. The method of claim 69,wherein the energy storage device comprises at least one inductor, atleast one capacitor, at least one battery or a combination thereof. 72.The method of claim 67, wherein the voltage pulse generation circuit iselectrically isolated from the load in the radio frequency domain. 73.The method of claim 43, wherein the voltage source applies the voltagepulses to at least one output power electrode of a plurality of solarcells to adjust a collective output power or a collective output currentsupplied by the solar cells via the output power electrode.
 74. Themethod of claim 73, wherein the plurality of solar cells is disposed ina series device configuration, a parallel device configuration or acombination thereof.
 75. The method of claim 73, wherein the pluralityof solar cells comprise a solar panel.
 76. The method of claim 43,wherein application of the voltage pulses to the output power electrodeincreases the output power or the output current of the solar cell by upto fifty percent under low light conditions.
 77. The method of claim 43,wherein application of the voltage pulses to the output power electrodeincreases the output power or the output current of the solar cell bymore than fifty percent under low light conditions.
 78. The method ofclaim 43, wherein application of the voltage pulses to the output powerelectrode increases the output power or the output current of the solarcell by up to twenty percent under high intensity light conditions. 79.The method of claim 43, wherein application of the voltage pulses to theoutput power electrode increases the output power or the output currentof the solar cell between twenty percent and fifty percent.
 80. Themethod of claim 43, wherein application of the voltage pulses to theoutput power electrode increases the output power or the output currentof the solar cell by more than fifty percent.
 81. The method of claim43, wherein application of the voltage pulses to the output powerelectrode accelerates a mobility of an electron and a hole of at leastone first electron-hole pair in the solar cell.
 82. The method of claim43, wherein application of the voltage pulses to the output powerelectrode provides electrons for filling at least one trap disposedbetween a valence band of the solar cell and a conduction band of thesolar cell.
 83. The method of claim 43, wherein the output power or theoutput current is based upon an intensity of light incident on the solarcell, the voltage pulses applied to the solar cell, a thickness of thesolar cell, a pulse width of the voltage pulses, a frequency of thevoltage pulses, or a combination thereof.
 84. The method of claim 43,wherein the voltage source applies the voltage pulses to the solar cellwithout structural modification of the solar cell.
 85. A method forincreasing solar cell efficiency, comprising: coupling a voltage pulsegeneration circuit with an output power electrode of a solar cell, thevoltage pulse generation circuit for applying one or more voltage pulseswith a positive magnitude to the output power electrode of the solarcell to adjust an output power or an output current supplied by thesolar cell via the output power electrode.
 86. The method of claim 85,wherein the voltage pulse generation circuit applies the voltage pulsesacross a pair of output power electrodes of the solar cell, the outputpower or the output current being supplied via the pair of output powerelectrodes.
 87. The method of claim 85, wherein application of thevoltage pulses to the output power electrode generates an electric fieldat the solar cell.
 88. The method of claim 87, wherein the electricfield is generated in a first direction being in a same direction as apolarity of the output power electrode for increasing the output poweror the output current supplied by the solar cell.
 89. The method ofclaim 88, wherein the electric field generated in the first directionaccelerates a mobility of an electron and a hole of at least one firstelectron-hole pair in the solar cell.
 90. The method of claim 87,wherein the electric field is generated in a second direction being inan opposite direction of as a polarity of the output power electrode fordecreasing the output power or the output current supplied by the solarcell.
 91. The method of claim 90, wherein the electric field generatedin the second direction decreases a mobility of an electron and a holeof at least one second electron-hole pair in the solar cell.
 92. Themethod of claim 85, wherein the voltage pulses have a uniform positivemagnitude.
 93. The method of claim 85, wherein the voltage pulses havean amplitude within an amplitude range between 100 Volts and 500 Volts,a frequency within a frequency range between 20 KHz and 200 KHz, aperiod within a period range between 5 microseconds and 50 microseconds,a nominal duty cycle in a duty cycle range between 0.1% and 10% or acombination thereof.
 94. The method of claim 85, wherein the voltagepulse generation circuit comprises a switching circuit for applying asupplied voltage signal to the output power electrode as the voltagepulses.
 95. The method of claim 94, wherein the switching circuitcomprises a switching transistor.
 96. The method of claim 94, whereinthe supplied voltage signal comprises a constant voltage signal.
 97. Themethod of claim 94, wherein a voltage source circuit is configured tosupply the supplied voltage signal to the switching circuit.
 98. Themethod of claim 97, wherein the switching circuit is at least partiallyintegrated with the voltage source circuit.
 99. The method of claim 94,wherein the switching circuit is configured to apply the suppliedvoltage signal to the output power electrode as the voltage pulses byalternating between a first switching mode for closing a current pathbetween the voltage source circuit and the output power electrode and asecond switching mode for opening the current path.
 100. The method ofclaim 99, further comprising a pulse generator circuit for providing acontrol signal to a control electrode of the switching circuit toalternate the switching circuit between the first and second switchingmodes.
 101. The method of claim 99, further comprising a control circuitfor adjusting a switching frequency between the first switching mode andthe second switching mode, a first duration of the first switching mode,a second duration of the second switching mode, a duty cycle of thefirst switching mode and the second switching mode, a first repetitionrate of the first switching mode, a second repetition rate of the secondswitching mode or a combination thereof.
 102. The method of claim 101,wherein the control circuit adjusts the switching frequency to be withina frequency range between 20 KHz and 200 KHz, the first duration to bein a first duration range between 10 nanoseconds and 2000 nanoseconds,the second duration to be in a second duration range between 10nanoseconds and 2000 nanoseconds, the duty cycle of the voltage pulsesto be within a duty cycle range between 0.1% and 10% or a combinationthereof.
 103. The method of claim 101, wherein the control circuit is atleast partially integrated with the voltage source circuit, theswitching circuit or both.
 104. The method of claim 85, wherein thevoltage pulse generation circuit is electrically isolated from theoutput power electrode in the radio frequency domain.
 105. The method ofclaim 85, further comprising a control circuit for adjusting a frequencyof the voltage pulses, the magnitude of the voltage pulses, a period ofthe voltage pulses, a repetition rate of the voltage pulses, a dutycycle of the voltage pulses, a duration of the voltage pulses or acombination thereof.
 106. The method of claim 105, wherein the controlcircuit adjusts the frequency to be within a frequency range between 20KHz and 200 KHz, the magnitude to be within an amplitude range between100 Volts and 500 Volts, the period to be within a period range between5 microseconds and 50 microseconds, the duty cycle to be within a dutycycle range between 0.1% and 10%, the duration to be in a duration rangebetween 10 nanoseconds and 2000 nanoseconds or a combination thereof.107. The method of claim 105, further comprising a sensor system formonitoring the output power, the output current, an output voltage ofthe solar cell or a combination thereof, wherein the control circuitadjusts the frequency of the voltage pulses, the magnitude of thevoltage pulses, the period of the voltage pulses, the repetition rate ofthe voltage pulses, the duty cycle of the voltage pulses, the durationof the voltage pulses or a combination thereof based upon at least oneof the monitored output power, the monitored output current and themonitored output voltage.
 108. The method of claim 105, wherein thecontrol circuit is at least partially integrated with the voltage pulsegeneration circuit.
 109. The method of claim 85, wherein the solar cellis configured to provide the output power or the output current to aload via the output power electrode.
 110. The method of claim 109,wherein the load converts the output power or the output currentsupplied by the solar cell into an alternating current voltage orcurrent.
 111. The method of claim 109, further comprising an energystorage device for mitigating voltage drop-out at the load duringapplication of a selected voltage pulse to the output power electrode.112. The method of claim 111, wherein the energy storage device storesthe output power or the output current supplied by the output powerelectrode as stored electrical energy between adjacent voltage pulsesand provides the stored electrical energy to the load during applicationof the selected voltage pulse to the output power electrode.
 113. Themethod of claim 111, wherein the energy storage device comprises atleast one inductor, at least one capacitor, at least one battery or acombination thereof.
 114. The method of claim 109, wherein the voltagepulse generation circuit is electrically isolated from the load in theradio frequency domain.
 115. The method of claim 85, wherein the voltagesource applies the voltage pulses to at least one output power electrodeof a plurality of solar cells to adjust a collective output power or acollective output current supplied by the solar cells via the outputpower electrode.
 116. The method of claim 115, wherein the plurality ofsolar cells is disposed in a series device configuration, a paralleldevice configuration or a combination thereof.
 117. The method of claim115, wherein the plurality of solar cells comprise a solar panel. 118.The method of claim 85, wherein application of the voltage pulses to theoutput power electrode increases the output power or the output currentof the solar cell by up to fifty percent under low light conditions.119. The method of claim 85, wherein application of the voltage pulsesto the output power electrode increases the output power or the outputcurrent of the solar cell by more than fifty percent under low lightconditions.
 120. The method of claim 85, wherein application of thevoltage pulses to the output power electrode increases the output poweror the output current of the solar cell by up to twenty percent underhigh intensity light conditions.
 121. The method of claim 85, whereinapplication of the voltage pulses to the output power electrodeincreases the output power or the output current of the solar cellbetween twenty percent and fifty percent.
 122. The method of claim 85,wherein application of the voltage pulses to the output power electrodeincreases the output power or the output current of the solar cell bymore than fifty percent.
 123. The method of claim 85, whereinapplication of the voltage pulses to the output power electrodeaccelerates a mobility of an electron and a hole of at least one firstelectron-hole pair in the solar cell.
 124. The method of claim 85,wherein application of the voltage pulses to the output power electrodeprovides electrons for filling at least one trap disposed between avalence band of the solar cell and a conduction band of the solar cell.125. The method of claim 85, wherein the output power or the outputcurrent is based upon an intensity of light incident on the solar cell,the voltage pulses applied to the solar cell, a thickness of the solarcell, a pulse width of the voltage pulses, a frequency of the voltagepulses, or a combination thereof.
 126. The method of claim 85, whereinthe voltage source applies the voltage pulses to the solar cell withoutstructural modification of the solar cell.
 127. A computer programproduct for increasing solar cell efficiency, the computer programproduct being encoded on one or more non-transitory machine-readablestorage media and comprising: instruction for applying one or morevoltage pulses with a positive magnitude to an output power electrode ofa solar cell via a voltage pulse generation circuit, the voltage pulsesfor adjusting an output power or an output current supplied by the solarcell via the output power electrode.
 128. The computer program productof claim 127, wherein said instruction for applying comprisesinstruction for applying the voltage pulses across a pair of outputpower electrodes of the solar cell, the output power or the outputcurrent being supplied via the pair of output power electrodes.
 129. Thecomputer program product of claim 127, wherein application of thevoltage pulses to the output power electrode generates an electric fieldat the solar cell.
 130. The computer program product of claim 129,wherein the electric field is generated in a first direction being in asame direction as a polarity of the output power electrode forincreasing the output power or the output current supplied by the solarcell.
 131. The computer program product of claim 130, wherein theelectric field generated in the first direction accelerates a mobilityof an electron and a hole of at least one first electron-hole pair inthe solar cell.
 132. The computer program product of claim 129, whereinthe electric field is generated in a second direction being in anopposite direction of as a polarity of the output power electrode fordecreasing the output power or the output current supplied by the solarcell.
 133. The computer program product of claim 132, wherein theelectric field generated in the second direction decreases a mobility ofan electron and a hole of at least one second electron-hole pair in thesolar cell.
 134. The computer program product of claim 127, wherein thevoltage pulses have a uniform positive magnitude.
 135. The computerprogram product of claim 127, wherein the voltage pulses have anamplitude within an amplitude range between 100 Volts and 500 Volts, afrequency within a frequency range between 20 KHz and 200 KHz, a periodwithin a period range between 5 microseconds and 50 microseconds, anominal duty cycle in a duty cycle range between 0.1% and 10% or acombination thereof.
 136. The computer program product of claim 127,wherein the voltage pulse generation circuit comprises a switchingcircuit for applying a supplied voltage signal to the output powerelectrode as the voltage pulses.
 137. The computer program product ofclaim 136, wherein the supplied voltage signal comprises a constantvoltage signal.
 138. The computer program product of claim 136, whereinsaid instruction for applying one or more voltage pulses includesinstruction for applying the supplied voltage signal to the output powerelectrode as the voltage pulses by alternating between a first switchingmode for closing a current path between the voltage source circuit andthe output power electrode and a second switching mode for opening thecurrent path.
 139. The computer program product of claim 138, furthercomprising instruction for providing a control signal to a controlelectrode of the switching circuit to alternate the switching circuitbetween the first and second switching modes.
 140. The computer programproduct of claim 138, further comprising instruction for adjusting aswitching frequency between the first switching mode and the secondswitching mode, a first duration of the first switching mode, a secondduration of the second switching mode, a duty cycle of the firstswitching mode and the second switching mode, a first repetition rate ofthe first switching mode, a second repetition rate of the secondswitching mode or a combination thereof.
 141. The computer programproduct of claim 140, wherein said instruction for adjusting includesinstruction for adjusting the switching frequency to be within afrequency range between 20 KHz and 200 KHz, the first duration to be ina first duration range between 10 nanoseconds and 2000 nanoseconds, thesecond duration to be in a second duration range between 10 nanosecondsand 2000 nanoseconds, the duty cycle of the voltage pulses to be withina duty cycle range between 0.1% and 10% or a combination thereof. 142.The computer program product of claim 127, further comprisinginstruction for adjusting a frequency of the voltage pulses, themagnitude of the voltage pulses, a period of the voltage pulses, arepetition rate of the voltage pulses, a duty cycle of the voltagepulses, a duration of the voltage pulses or a combination thereof. 143.The computer program product of claim 142, wherein said instruction foradjusting includes instruction for adjusting the frequency to be withina frequency range between 20 KHz and 200 KHz, the magnitude to be withinan amplitude range between 100 Volts and 500 Volts, the period to bewithin a period range between 5 microseconds and 50 microseconds, theduty cycle to be within a duty cycle range between 0.1% and 10%, theduration to be in a duration range between 10 nanoseconds and 2000nanoseconds or a combination thereof.
 144. The computer program productof claim 142, further comprising monitoring the output power, the outputcurrent, an output voltage of the solar cell or a combination thereof,wherein said instruction for adjusting includes instruction foradjusting the frequency of the voltage pulses, the magnitude of thevoltage pulses, the period of the voltage pulses, the repetition rate ofthe voltage pulses, the duty cycle of the voltage pulses, the durationof the voltage pulses or a combination thereof based upon at least oneof the monitored output power, the monitored output current and themonitored output voltage.
 145. The computer program product of claim127, wherein the solar cell is configured to provide the output power orthe output current to a load via the output power electrode.
 146. Thecomputer program product of claim 145, wherein the load converts theoutput power or the output current supplied by the solar cell into analternating current voltage or current.
 147. The computer programproduct of claim 145, further comprising an energy storage device formitigating voltage drop-out at the load during application of a selectedvoltage pulse to the output power electrode.
 148. The computer programproduct of claim 147, wherein the energy storage device stores theoutput power or the output current supplied by the output powerelectrode as stored electrical energy between adjacent voltage pulsesand provides the stored electrical energy to the load during applicationof the selected voltage pulse to the output power electrode.
 149. Thecomputer program product of claim 127, wherein said instruction forapplying the voltage pulses comprises instruction for applying thevoltage pulses to at least one output power electrode of a plurality ofsolar cells to adjust a collective output power or a collective outputcurrent supplied by the solar cells via the output power electrode. 150.The computer program product of claim 149, wherein the plurality ofsolar cells is disposed in a series device configuration, a paralleldevice configuration or a combination thereof.
 151. The computer programproduct of claim 149, wherein the plurality of solar cells comprise asolar panel.
 152. The computer program product of claim 127, whereinapplication of the voltage pulses to the output power electrodeincreases the output power or the output current of the solar cell by upto fifty percent under low light conditions.
 153. The computer programproduct of claim 127, wherein application of the voltage pulses to theoutput power electrode increases the output power or the output currentof the solar cell by more than fifty percent under low light conditions.154. The computer program product of claim 127, wherein application ofthe voltage pulses to the output power electrode increases the outputpower or the output current of the solar cell by up to twenty percentunder high intensity light conditions.
 155. The computer program productof claim 127, wherein application of the voltage pulses to the outputpower electrode increases the output power or the output current of thesolar cell between twenty percent and fifty percent.
 156. The computerprogram product of claim 127, wherein application of the voltage pulsesto the output power electrode increases the output power or the outputcurrent of the solar cell by more than fifty percent.
 157. The computerprogram product of claim 127, wherein application of the voltage pulsesto the output power electrode accelerates a mobility of an electron anda hole of at least one first electron-hole pair in the solar cell. 158.The computer program product of claim 127, wherein application of thevoltage pulses to the output power electrode provides electrons forfilling at least one trap disposed between a valence band of the solarcell and a conduction band of the solar cell.
 159. The computer programproduct of claim 127, wherein the output power or the output current isbased upon an intensity of light incident on the solar cell, the voltagepulses applied to the solar cell, a thickness of the solar cell, a pulsewidth of the voltage pulses, a frequency of the voltage pulses, or acombination thereof.
 160. The computer program product of claim 127,wherein said instruction for applying the voltage pulses includesinstruction for applying the voltage pulses to the solar cell withoutstructural modification of the solar cell.